Spiny Oysters Spondylus gaederopus
Spondylus gaederopus is a species of marine bivalve mollusc, a thorny oyster in the family Spondylidae. This species is endemic to the Mediterranean Sea. Spondylus gaederopus attaches itself to the substrate with its lower valve, which is usually white, while the upper valve is usually purple. Specimens that are all white, or all purple do, however, exist.